1. Field of the Invention
The present invention relates to a lens barrier which opens and closes a lens aperture provided at a front end of a lens barrel.
2. Description of the Related Art
Recently, compact cameras tend to have a built-in lens barrier which opens and closes the lens aperture. The lens barrier essentially includes one barrier plate or a plurality of barrier plates which move in front of the lens aperture to open and close the same in association with the movement of a photographing lens between a retracted position in which the photographing lens is retracted in a camera body and a photographing position in which a picture of an object can be taken.
The number of the barrier plates can be decreased to one or two if there is enough space to accommodate the barrier plate or plates when they are retracted from the lens aperture. However, at the same time as recent compact cameras are becoming smaller, their lens apertures are becoming larger. This makes it difficult to provide a space large enough for accommodating the barrier plates.
A compact camera having four barrier plates is also available on the market. However, in this known camera, two of the four barrier plates move by parallel translation to each other and the other two rotate, thus resulting in a complicated construction.
Furthermore, conventional barriers must be actuated manually when the user wants to open and close the lens aperture. It is difficult to automatically move the barrier plates in association with the movement of the photographing lens between the retracted position and the photographing position.
In addition, in recent compact cameras recently there is a tendency toward increasing the size of the aperture of the lens to accommodate an increase in a focal length thereof, which results in an increase of the lens diameter. This in turn leads to an increase of the diameter of the barrier plates (blades). However, there is a need for a decrease in the diameter of the lens barrel. Even if the barrier is composed of only two barrier blades, it is difficult to provide a space in which the barrier blades and the drive mechanism thereof can be rotated and accommodated in the lens barrel.
There is also known, a zoom lens camera having a large magnification that has a lens cap which is also used as a lens barrier thus barrier blades are not required.
However, the attachment and detachment of a lens cap is troublesome and can cause a photographer to miss a chance at a good shot or to lose the lens cap. Accordingly, it is desirable to provide a barrier in a zoom lens camera having large magnification capability.